Shrouding cap for sparking plugs



Sept. 26, 1933. WERNER 1,928,520

SHROUDING CAP FOR SFARKING PLUGS Filed Nov. 9. 1931 Patented Sept. 26, 1933' UNITED STATES PATENT oFncE Gustav Werner, Stuttgart, Germany, amignor Robert Bosch Stuttgart,

Germany Application November 9, 1931, Serial No. 573,977,

and in Germany November 28, 193i 8 Claims. 123-169) stance the plug is not visible when the cap is to be put in place.

According to this invention, a particularly simple construction, which during rough usage always remain firm and secure, is attained by a retaining spring which is held by a member bearing against the metallic cap and which, can be tensioned.

An example of construction of the invention is illustrated in the accompanying drawing.

In the drawing, 1 is the sparking-plug, in which the insulating body 4 carrying the central electrode 3 is secured by the nut 2. The protective cap 5 is placed over the part of the insulating body 4 which projects above the nut '2, and is seated on the latter. The cap has on its dome an external lug or projection 6, which serves to hold a nut '7 in its position. Into this nut is screwed the screw-bolt 8, which is movably attachedtotheretainingspringi). Thetwo ends of the spring are bent to form hooks 10, which are inserted in two conical openings 11 in a plate 12. The body of the sparking-plug 1 has a collar 13, which acts as an abutment for the plate.

This construction has the advantage that the retaining spring canbeput onin anuntensioned.

condition without using any force and then tightenedup. Bythismeanstheuseoistrongsprings, which, without the tensioning device, could only 'beputonwiththe aidoi atoolismadepossible.

I declarethat what I claim is:

1. A shrouding cap for sparking-plugs comprising in' combination a hollow cap, a bow spring,meanstoengagetheireeendsofsaid spring with an abutment on the plug and telescopic tensioning means between said bow and said cap. I v 2. A shrouding cap for sparking-plugs comprising in combination a hollowcap, an abutment onsaidcap,abowspring,expansionnutandbolt o meansthreaded onsaidbowsprlngandmeans to engage the tree ends 0! the said how spring with an abutment on the plug.

'3. A shrouding cap for sparking-plugs comprising in combination a hollow cap, an abutment onsaidcamabowspmingexpansionnutandbolt means threaded on said bow spring and engaging the abutment on the cap, a ring engaging behind a flange on the plug and engaged by the free ends of said how spring.

4. As an article of manufacture a tensioning spring for the caps of sparking-plugs comprising a bow, hooked ends on the bow, and an expansion nut and bolt threaded on the how.

5. A shrouding cap for sparking plugs comprising in combination a hollow cap, a spring member engaging an abutment on the plug and extending over said cap anda tension device between said spring member and said cap for adjusting the tension of said spring member and transmitting the tension thereof to said cap.

6. The combination with a spark plug having a circumferential projection intermediate its outer terminal and the portion of the plug engaging the engine cylinder, of a cap extending over the outer terminal of the plug and freely engaging the plug body, a ring member rotatably engaging about the body of the plug beneath and against the circumferential projection thereon, a bow spring having its ends secured in said ring member and extending in spaced relation over the top of said cap, and a tensioning device between said bowspringand thetopofsaidcap.

'l. The combination as set forth in claim 6 and in which said tensioning device comprises nutand-bolt means threaded on said how spring and ensfla'insthetop of saidcap. v

8. Thecombinationasset Iorthinclaim 6 and inwhichsaidtensioningdevicecomprisesa threaded nut mounted in fixed angular position onthetopoisaidcapandaboltsecuredtosaid bow spring and engaging said nut.

GUSTAV 

